Giant 2.5 GB JP2 image: How to tile it?

Question

I have a single 2.5 GB JP2 image of a city that I need to split into tiles, which I'll then process to create flight simulation scenery.

Google as I might, I can't find the solution.

The JP2 apparently has GIS XML data embedded, which doesn't affect me either way, since I don't need it. All I'm trying to do is break the image down into x-number of preferably 2048 x 2048 tiles.

A utility to do this in either OSX or Win7 would be great.

Ideas?

Thanks!

Answer 1

You can write a simple shell script and use gdal_translate utility to chop the tiles. On Mac, get the GDAL build from here. On Windows,the best way to get GDAL is via the OSGeo4W installer. In the following script, you need to replace following things

• XDIM and YDIM with your source jp2 X and Y dimensions
• gdal_translate with the actual path on your system
• input.jp2 with path to your input file.

Save the script in a text file called script.sh. Open a Terminal and run 'bash script.sh'. That will create the tiles in a directory called tiles/ . The script is copied from here with a little modification for your purpose.

#!/bin/bash
mkdir tiles

XDIM=24000
YDIM=24000
BLOCKSIZE=2048
XPOS=0
YPOS=0
BLOCKNO=0
while [ $YPOS -le $YDIM ]
do
while [ $XPOS -le $XDIM ]
  do
    echo "$XPOS $YPOS : ${BLOCKNO}.tif"
    gdal_translate -of GTiff -srcwin $XPOS $YPOS $BLOCKSIZE $BLOCKSIZE input.jp2 \
      tiles/${BLOCKNO}.tif
    BLOCKNO=`echo "$BLOCKNO + 1" | bc`
    XPOS=`echo "$XPOS + $BLOCKSIZE" | bc`
  done
YPOS=`echo "$YPOS + $BLOCKSIZE" | bc`
XPOS=0
done